Polyalkylene glycol dibenzoates, and resinous compositions plasticized therewith



United States Patent 3,110,663 PGLYALKYLENE GLYCOL DHBENZQATEl,

AND RESINOUS CGMPQSHTION?) PLASTI- ClZEl) THEREWHTH Howard F, Reeves, Jrz, Raymond W. lngwalson, and .lohn L. Rose, .ln, Chattanooga, Tenn, assignors to Tennessee Products and Chemical Corporation, Nashville, Tenn, a corporation of Tennessee No Drawing. Griginal application duly 30, 1953, Ser. No. 371,423, now Patent No. 2,956,978, dated Get. 18, 1960. Divided and this application Aug. 6, 1958, Ser.

1 Claim.

This invention relates to compositions of matter having unusual utility in plasticizing resinous compositions, particularly polyvinyl chloride and copolymers, vinyl chloride and vinyl acetate and the like. More particularly, this invention relates to polyalkylene glycol dibenzoates, and resinous compositions plasticized therewith.

This is a division of our copend-ing application Serial No. 371,423, filed July 30, 1953, now US. Patent No. 2,956,978.

Generally, in selecting a compound which would be suitable as a plasticizer, the compound selected should have a high boiling point, low volatility, a low freezing point, a mild or pleasant odor, or no odor at all, be compatible with resinous compositions and be non-toxic. A plasticizer should also be of light color or be colorless, and comprise the proper degree of polarity.

In the past, dibenzoates of ethylene glycol, diethylene glycol, and triethylene glycol have been synthesized. The latter two compounds possess certain characteristics such as high boiling points, good stability, practically no odor and good compatibility with certain resins, which makes them desirable as plasticizers. On the other hand, the above me bers of this series are solids at room temperature; thus, it would normally be expected that if a process Were devised for producing the higher members of this glycol series, they Would also be solids at room temperature. The dibenzoate or diethylene glycol has another disadvantage in that it has the rare quality of possessing two distinct freezing points, namely 17.2 C. and 29.1 C., the latter freezing point form being the more stable.

In general, it is very undesirable for a plasticizer to have a high freezing point where low temperature flexibility is of importance in the finished plastic item. In addition, solid plasticizers often incur handling difliculties from the standpoint of having to melt large cont-ainers of the frozen item. Certain resin compositions are prepared, stored, shipped and used as liquid dispersions of fine resin solids in a plasticizer. When these materials freeze, they must be melted with extreme caution as excessive heat will cause prematurengelation and solidification and results in complete loss of material.

'In the prior art production of glycol esters, the glycol is reacted with an organic acid in the presence of a hydrogen ion catalyst, the following reaction being typical:

Diethylenc glycol dibenzoatc A secondary reaction takes place that splits or decomposes the product to some extent to yield:

' i Q d O Ethylene glycol dibcnzoate In order to accomplish the above reaction in a reasonable period of time, heat is usually applied to the reactants. In this instance, the presence of the catalyst, sulfuric acid or toluene sulfonic acid, in the reaction zone, discolor-s the esters to a straw or dark color. It has been found that the esters produced according to the above process do not lend themselves Well to conventional bleaching treatments and thus, controlled fractional distillation of the resulting esters is substantially the only way to obtain a pure light colored product.

In general, even if heat is applied, the reaction described above proceeds slowly and the esters tend to darken as the reaction proceeds. When using dipropylene glycol in the above reaction, We have found it necessary to accept esterification in the neighborhood 05E 50% of the theoretical, in order to obtain a reasonably light colored ester. After about ten hours and when approximately 80% of the theoretical Water is removed, the esterification reaction stops and the resulting black viscous material which remains in the reaction zone is unacceptable as a plasticizer.

To overcome the disadvantages inherent in the process heretofore described, the classic Schotten and Baumann reaction has been used in the prior art. and Bauzmann method, poor yields are to be expected;

since, in the reaction the benzoyl chloride hydrolyzes to benzoic acid; thus, yields of desired esters in the neighborhood of of theoretical yield would be considered In this Schotten good. The resulting ester from this process usually has an off-color and odor, and will, in most instances, contain half-esters which are extremely diflicult and in some instances impossible to separate.

The use of pyridine in combination with an aroyl chloride and a hydroxy compound has been proposed; however, this procedure does not lend itself to large scale production of low cost esters since the pyridine is prohibitive in cost.

By both of the above described prior art methods, it is extremely difficult, if not impossible, in most instances, to produce anything more than nominal quantities of a secondary glycol ester, i.e. an ester from a glycol in which the hydroxy groupis attached to a saturated carbon atom in the chain, the carbon containing only one hydrogen atom.

It is a primary object of our invention to produce plasticizers which have the advantages of the prior art plasticizers and substantially none of the disadvantages thereof.

Another object of our invention is to provide new compositions of matter.

Another object of our invention is to provide superior plasticized resinous products.

Other and further objects and advantages of our invention will become apparent from the following description of embodiments thereof.

Contrary .to prior art beliefs and practices, we have been able, through a new process, to produce dibe-nzoates of glycols which are liquids at room temperature and have unusual properties as plasticizers. According to our invention, these dibenzoates of glycols are produced by intimately contacting a polyalkylene glycol with an aro-yl halide in substantially equivalent proportions. When commingled, the aroyl halide reacts with all of the hydroxy groups of the glycol and through the evolution of hydrogen halide, which leaves or is withdrawn from the reaction zone substantially at the rate at which it is formed, substantially complete esterification of the glycol is accomplished. Heat may be applied to the reactants to increase the speed of reaction and it is recommended that the reactants be maintained at a temperature of from 80 C. to 125 C. Below approxirnatcly 50 C. the reaction proceeds extremely slowly and above about 175 C. there is a tendency for part of the aroyl halide to be volatilized with the hydrogen halide. If desired, the reaction zone may be evacuated to induce removal of the hydrogen halide. ln event that either heat or vacuum is applied to the reaction zone, it may be found desirable to provide a reflux condenser to return the somewhat volatile aroyl halide to the reaction zone.

Generally, a mole ratio depending on the number of hydroxy groups should be established even through an excess of aroyl halide may be found desirable. It is also preferable to add the glycol to the aroyl halide since the halide impurities in the resulting product are diminished thereby. Further, if large amounts of the glycol are added to the relatively warm chemicals in the reaction zone, there is a tendency for the aroyl halide to be entrained with the hydrogen halide and to be carried from the reaction zone therewith. After the esterification reaction is completed and if no vacuum is used during the reaction, small amounts of hydrogen halide gas may be present the ester and may be removed therefrom by evacuating the reaction zone while agitating the ester. To remove traces of the hydrogen halide and the aroyl halide, the ester may then be washed in a mild aqueous alkaline bath. The glycol esters produced according to our invention are insoluble in and heavier than water, thus these esters may be subjected to many alkaline or water washes if desired.

A good yield may also be accomplished by mixing the glycol with aroyl halide, at a temperature below which these reactants will react and then feeding small incred ments of the thoroughly commingled reactants into a reaction zone where they are heated and reacted. in this event, the hydrogen halide is withdrawn as described heretofore.

The es erification reaction described above may be illustrated as follows:

where R represents an alkylene group or groups, such as methylene, ethylene, ethylidene, etc. and Y represents any interger from 0 up, while X represents a halogen, and R represents an aroyl group or groups or a substituted aroyl group or groups, for example benzoyl or chlorobenzoyl. it has been found that molecules Where Y is as high as 15 form suitable plasticizers.

Substituting in the above formula, a dipropylene glycol dibenzoate may be made from dipropylene glycol and benzoyl chloride; the reaction being as follows:

Further, tripropylene glycol dibenzoate may be made from tripropylene glycol and tetra propylene glycol d1- benzoate may be made from tetra propylene glycol, etc.

Mixtures of these glycols, as they occur in commerce,

work very smoothly in the above reaction to yield esters useful as plasticizers. Thus, the new compounds which we have devised may be expressed as:

where Y represents an integer of 1 to 15 and R and R represent phenyl or chlorine substituted phenyl. It is equally obvious that the dibenzoates of higher polyethylene glycols or mixtures thereof can be made by the above reaction. Instead of benzoyl halide, one may use chlorobenzoyl halides such as meta, ortho, para, 2-4 dichloro, 3-5 dichloro benzoyl halide or mixtures thereof. Also, other substituted benzoyl halides such as methyl-, ethyl-, nitro-, etc. benzoyl chlorides may be used with such mixtures as benzoyl chloride and chlorobe-nzoyl chloride yielding products of improved properties.

In the above reaction, using a benzoyl chloride or a substituted benzoyl chloride, over of theoretical hydrogen chloride is evolved as a pure gas and can be readily recovered as a byproduct by any prior art method.

Details of the practice of this invention are set forth with respect to the following examples:

EXAMPLE I Ten moles of diethylene glycol (1061.2 grams) were added over an eighty-eight minute period to 20.2 moles (3536 grams) of metachlorobenzoyl chloride at 98-105" C. in a three-necked five liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the diethylene glycol being added through Ten moles of diethylene glycol (1061.2 grams) were added over 1% hour period to a mixture of 10.1 moles (1776 grams) of predominantly meta-chlorobenzoyl chloride and 10.1 moles (1423 grams) of benzoyl chloride at 105-110 C. in a three-necked five liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the diethylene glycol being added through the dropping funnel as the chlorobenzoyl chloride and benzoyl chloride were agitated. The hydrogen chloride gas which formed during the reaction passed through the reflux condenser and was trapped in water. After all of the diethylene glycol was added, stirring was continued for 4 /2 hours and the temperature of the chemicals within the flask was maintained between 106150 C. The product was next given an alkaline wash Na CO and water) followed by a water wash. The product was a water white liquid and consisted of a mixture of diethylene glycol dibcnzoate, diethylene glycol bis-meta-chlorobenzoate and diethylene glycol benzoate-meta-chlorobenzoate. The yield was 97.5 of the theoretical based on diethylene glycol.

EXAMPLE III Four moles of diethylene glycol (424.5 grams) were added over a forty-two minute period to 8.16 moles (1146 grams) of benzoyl chloride at IOU-167 C. in a threenecked two liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the diethylene glycol being added through the dropping funnel as the benzoyl chloride was agitated. The hydrogen chloride gas which formed during the reaction passed through the reflux condenser and was trapped in water. After all of the diethylene glycol was added, stirring was continued for five hours and the temperature of the chemicals within the flask was maintained at lQ2140 C. The product was next given an alkaline wash (20% Na CO and water) followed by a water wash. The yield of diethylene glycol dibenzoate, a water white liquid was 98.5 of the theoretical yield.

EXAMPLE IV Four moles of dipropylene glycol (536.8 grams) were added over a one and one half hour period to 8.16 moles (1150 grams) of benzoyl chloride at 109125 C. in a three-necked three liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel,

the dipropylene glycol being added through the dropping EXAMPLE V roe moles'of polyethylene glycol (600 gramsaverage molecular weight 209) were added over a period of twenty-five minutes to 6.12 moles (857 grams) of benzoyl chloride at 104l30 C. in a three-necked two liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the polyethylene glycol being added through the dropping funnel as the benzoyl chloride was agitated. The hydrogen chloride gas which fonrned drring the reaction passed through the reflux condenser and was trapped in water. After all of the polyethylene glycol was added, stirring was continued for 3 hours and the temperature of the chemicals within the flask was maintained between 104140 C. The product was next given an alkaline wash (20% Na CO and water) followed by a water wash. The yield of polyethylene glycol dibenzoate, a water white liquid, was of the theoretical yield.

EXAMPLE VI Two moles of polyethylene glycol (400 grams-average molecular weight of 200 grams) were added over a one hour period to 4.1 moles (718 grams) of meta-chlorobenzoylczhlor-ide at 96l26 C. in a three-necked two liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the polyethylene glycol being added through the dropping funnel as the metach-lorobenzoyl chloride was agitated. The hydrogen chloride gas which formed during the reaction passed through the reflux condenser and was trapped in water. After all of the polyethylene glycol was added, stirring was continued for four and one-half hours and the temperature was maintained between 96l38 C. The product was next given an alkaline wash (20% Na CO and water) followed by a water wash. The yield of polyethylene glycol bis-meta-chlorobenzoate, a water White liquid, was 95% of the theoretical yield.

EXAMPLE VII One mole of polyethylene glycol (300 gramsaverage molecular weight of 300 grams) was added over a fortytwo minute period to 2.04 moles (287 grams) of benzoyl chloride at 869l C. in a three-necked one liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the polyethylene glycol being added through the dropping funnel as the benzoyl chloride was agitated. The hydrogen chloride gas which formed during the reaction passed through the reflux condenser and was trapped in water. After all of the polyethylene glycol =was added, stirring was continued for three hours and the temperature was maintained between 86-135 C. The product was next given an alkaline wash (20% Na CO and water) followed by a water wash. The yield of polyethylene glycol di benzoate, a water white liquid, was 97% of the theoretical yield.

EXAMPLE Vlll One mole of polyethylene glycol (400 grams-average molecular weight of 400 grams) was added over a one hour period to 2.04 moles (287 grams) of benzoyl chloride at 95400 C. in a three-necked one liter flask equipped with an agitator, a thermometer, a reflux condenser and a dropping funnel, the polyethylene glycol being added through the dropping funnel as the benzoyl three hours and the temperature was maintained between 97-l36 C. The product was next given an alkaline wash (26% Na CO and water) followed by a water wash. The yield of polyethylene glycol dibenzoate, a water-white li u' 1", was 96%" or" the theoretical yield. Dibenzoa s of glycols having a molecular weight from approximately 260 to approximately 760 are substantially water white liquids at room temperature, the physical characteristics of some 01" these esters being listed below.

8 The dipropylene glycol dibenzoate produced according to our invention and incorporated with a clear plastic as a Table I Sample (names below) (1) (2) (3) (5) Boiling Point, C 235 5 min 253 4 mm range 1 d. above 300 range 2.5 (1. above 300 gm. 225- 1.6 mm. mm 224- 2.3 mm.

Freeze Point, C

ND C

Acidity, mg. KOH/g Viscosity, cps. 25 0 Flash Point, C

glass -48". 1.5077.

glass 1.5252 l 53 9 *Taken at 20 C.

(1) Dipropylene glycol dibenzoate. (2) Dipropylene glycol bis-chlorobenzoate.

(3) Mixture of diethylene glycol dibenzoate, diethylene gl (4) Dibenzoate of polyethylene glycol (molecular weight 200). (5) B s-ehlorobenzoate of polyethylene glycol (molecular weight 200). (6) Drbenzoate of Polyethylene glycol (molecular weight 300). (7) Drbenzoate of polyethylene glycol (molecular weight 400).

The glycol esters produced according to our process were generally found to be compatible with and to plasticize various resins such as water insoluble vinyl resins, water insoluble cellulose esters and water insoluble cellulose others, the 'compatability with specific products being shown in Table II.

ycol bis-chloroben zoate and diethylene glycol benzoate-clilorobenzoate.

Table 11 Sample (Names below) (l) i (2) I (3) Ratio of resin to 1:1 3:1 Polyvinyl Chloride- O Polyvinyl Acetate C Vinyl Chloride-Acetate Copelrnerwith a plastic, the plastic becomes pliable, while sweating out of the ester does not occur until the plastic film comprises approximately 80% dipropylene glycol dibenzoate. Cellulose acetate films containing 30% by weight of dipropylene glycol dibenzoate are clear, transparent, free of oiliness and are flexible. Ethyl cellulose films y C ellulose Acetate Cellulose Butyrate Cellulose Acetate-B C ellulose Nitrate Ethyl Cellulose- Polystyrene containing 30% by weight of dipropylene glycol dibenzoate are exceptionally tough and do not craze or crack on flexing. Dipropylene glycol dibenzoate can be advantageously used in nitrocellulose compositions either alone or in admixture with other plasticizers and stabil- (l) Dipropylene glycol (libenzoate. (2) Dipropylene glycol bis-chlorobenzoatc.

(3) Mixture of diethylene glycol dibenzoate, diethylene glycol bischlorobenzoate and (liethylene glycol benzoate-chlorobenzoate.

Using dioctyl phthalate izers. Rubber hydrochloride film containing 30% dipropylene glycol dibenzoate is flexible and has good light stability properties. Other liquid glycol dibenzoates produced according to our invention exhibit similar properties.

It will be obvious to those skilled in the art that many variations may be made in the embodiments chosen for purpose of illustration without departing from the scope of our inventionvas defined by the appended claim.

We claim:

A plasticized composition comprising a plastic selected from the group consisting of polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, cellulose acetate, cellulose butyrate, cellulose acetate-butyrate, cellulose nitrate, ethyl cellulose and polystyrene, plasticized with a mixture of diethylene glycol dibenzoate, di-

as follows: ethylene bis-meta-chlorobenzoate and diethylene glycol PLASTIOIZED FILM TEST benzoate-meta-chlorobenzoate.

i g g g i yi pgi g g g References cited in the file of this patent VmylAcetate UNITED STATES PATENTS 2,480,185 Fife et al. Aug. 30, 1949 DPGDB DOP DPGDB DOP 2,726,947 Baumgartner Dec. 13, 1955 'll andsille Strength FOREIGN PATENTS ni ng ttti'ij'i 'a 385 o' '330 320 496,574 Great Britain Dec. 1, 1938 Shore Hardness 90 85 OTHER REFERENCES In the above film test, DPGDB represents dipropylene Modern Plastics Encyclopedia (1952), pages 698-699 glycol dibenzoate while DOP represents dioctyl phthalate. elied o 

